Polytunnels & Heated Greenhouses
29th Aug 2002
Having done a fair bit of travelling up to now judging shows all over the Country, I am always amazed at the sheer quality of some of the produce.
What did amaze me when I visited the Gateshead show during late July was the size of some of the vegetables for that time of year and particularly being located up in the north east corner of the country. The pot leeks were phenomenal as were the blanch leeks and even the carrots and Parsnips were really up to late August quality.
Of course the use of Polytunnels heated greenhouses and the use of re selected seed as well as the newer F1 hybrid varieties have all certainly contributed towards having crops maturing earlier. The beauty of a Polytunnel is the fact that not only can you produce crops earlier in the year, you can also extend the growing year at the back end of the season. One point to be always aware of with polytunnels, they can become ovens in the summer and fridges in the Winter; having said that, I would urge every grower who is keen on growing vegetables to have one.
I would go as far as to say that to become anywhere near the top in vegetable growing, polytunnels are a must. They must also be high up on the list of 'must have' for even the ordinary Kitchen gardener as the crops can be harvested so much earlier. Think how tasty new potatoes could be towards late April and think how nice your own home grown Kohl Rabbi and turnips would be harvested from your polytunnel during late October.
You don"t have to buy a huge hanger of a polytunnel to make a vast difference to the quality and size of your vegetables. Indeed I would say that the longer they go, the hotter they will get in the middle, particularly it you have not allowed for this by means of adequate ventilation. I have said before, rather than buying a forty or fifty foot long tunnel for leeks and onions you would be much better off purchasing two at twenty or twenty five foot so that you have more air movement inside them.
The sizes mentioned above are of course on the large side and anyone purchasing those will have plenty of land at their disposal to erect them on. However they can be purchased much smaller than this and with all the facilities of a larger one. There are some available with plastic fine netting on the inside which is covered over with polythene. This allows you to start the plants early and then when Spring moves on to Summer the polythene can be rolled up and the netting exposed to allow the breeze to circulate through your plants.
A Present from Santa?
This Christmas, why not let you family know that you would much prefer them to pool their money for a polytunnel for you rather than a host of smaller presents. Believe me the satisfaction you will get from owning one as well as the improvement in your vegetables could take you from the second division right through to the premier league in one season, something that you can't even achieve in football terms!
As I said earlier in the year my celery was very slow to take off after I planted it out much earlier than I would have usually done. However after giving it a couple of feeds of Vitax 3:0:1, the improvement was immediately noticeable. The growth rate was quick and the petioles or stalks were wide at the bottom. I have to say that when I have been visiting top growers gardens this year, nearly all of them were using this 3:0:1 high Nitrogen boost at different times of the year.
Personally, until this season, I have always been a bit wary of using high nitrogen feeds with celery knowing full well that I might get the growth so soft that it would eventually lead to heart rot. Heart rot of course is devastating to celery as it instantly stops you being able to show any heads of it. However since then I have been using Calcium Nitrate and/or liquid Calcium with great success to combat this problem. When growing celery for Chelsea in the large commercial greenhouses at Bangor in florist buckets, not one of the 30 plants succumbed to this cultural problem.
The greenhouse in question is old and has not been in use for some years so the ventilation system has completely jammed, this mean that there was no air flow at all within it. Temperatures in May often shot up to over 90°F inside it which even made me wilt. However once I got into the routine of using 5ml of Calcium Nitrate in a gallon of water every Monday night, it kept the problem totally at bay. A gallon was used between 8 to 10 plants and slowly trickled through the foliage down into the heart.
The secret is in getting calcium to the young emerging shoots of the celery heart, these are the ones that sweat and rot off as the cells die because of lack of calcium movement in them. Not dissimilar to the reason why blossom end rot is evident through lack of water, the calcium rushes through the plant elsewhere to save itself, leaving the fruits vulnerable. The main thing with the application of calcium nitrate and the manner that we grow and push celery to the limits is in the regularity of application. Make sure that you apply it once a week and the best way is to pick one particular night of the week, this will soon become a routine for you.